Grey partridges have declined by 91% in the UK since 1970. Chick survival is entirely dependent on insect availability in the first weeks of life, and loss of insect-rich field margins has caused catastrophic chick mortality across the UK.
Grey partridge chicks that cannot find adequate insect food in their first weeks either starve slowly or become hypothermic as they lack the energy to thermoregulate. Adults leading broods across pesticide-treated landscapes find insufficient invertebrate food despite intensive brooding behaviour. The 91% population decline represents one of the most severe welfare declines of any UK farmland bird.